# dev.writeToDisk

- **Type:** `boolean | ((filename: string) => boolean)`
- **Default:** `false`

Used to control whether the build artifacts of the development environment are written to the disk.

Rsbuild by default saves the build artifacts in the memory of the dev server, thereby reducing the overhead caused by file operations.

## Writing to Disk

You can choose to write the build output to disk, which is usually used for inspecting the content of the build output or configuring proxy rules for static assets.

Simply set the `dev.writeToDisk` option to `true`:

```ts
export default {
  dev: {
    writeToDisk: true,
  },
};
```

:::tip
Setting `writeToDisk: true` is used for viewing the build artifacts in a development environment. It does not change the behavior of the dev server. When accessing files through a browser, the dev server will still read the file content from memory.
:::

## Matching Specific Files

You can also set `dev.writeToDisk` to a function to match only certain files. When the function returns `false`, the file will not be written; when it returns `true`, the file will be written to disk.

For example, to write files to disk while excluding hot-update temporary files:

```ts
export default {
  dev: {
    writeToDisk: (file) => !file.includes('.hot-update.'),
  },
};
```
